Problem: What is the greatest common factor of $5$ and $25$ ? Another way to say this is: $\operatorname{gcf}(5, 25) = {?}$
Solution: The greatest common factor is the largest number that is a factor of both $5$ and $25$ The factors of $5$ are $1$ and $5$ The factors of $25$ are $1$ $5$ , and $25$ Thus, the greatest common factor of $5$ and $25$ is $5$. $\operatorname{gcf}(5, 25) = 5$